French Horizon Blue varied from a grayish light blue to a silvery light blue to an azure with all tones in between. Any light blue you want would be appropriate for one batch of clothing or another at some time, often multiple shades worn simultaneously.

So the answer just about any shade or tint of light blue.

Also 1915-1917, dark colored corduroy trousers were not uncommon as a wartime expedient due to a lack of horizon blue cloth. Horizon Blue cloth was reserved for kepis and over coats.

Hi all, I/m planning on painting a WW1 French infantryman and wondered if anyone had any suggestions as the best shade of blue/grey to use for the uniform? I use Vallejo paints and have a wide range!Any advice/suggestions most welcome! Thanks